In fabricating devices for use at cryogenic temperatures such as for storing a cryogenic fluid (e.g. liquid helium or liquid hydrogen), it is conventional to use a dewar of the type shown in U.S. Pat. No. 4,988,014.
In fabricating a dewar of the type shown in the aforementioned patent it is conventional to take the inner vessel and cover it with a suitable insulation such as a multilayer composite of metal and plastic. The multilayer insulation is used on the internal supporting piping and all internal parts can be insulated to prevent heat infiltration and loss of cryogen stored in the inner vessel by evaporation.
The problem with using multilayer insulation in conjunction with a cold mass (e.g. inner vessel) or a shield which is sometimes disposed between the inner and outer vessels is that construction and insulation of the cold mass cannot be done simultaneously. Furthermore, the cold mass or shields cannot be removed from the insulation without damage to the insulation. Lastly, items that cannot be rotated and items with non-circular cross sections cannot be insulated with a better distribution of insulation than could be accomplished if the devices could be rotated about a longitudinal axis.